The present invention is generally related to a tilt-trim assembly for marine propulsion devices, and, more particularly, to a tilt-trim assembly for a stern drive propulsion system.
In marine propulsion devices, it is common to have hydraulic cylinder/piston assemblies located externally of the boat for effecting pivotal movement of the propulsion unit relative to its mounting bracket. For example, in marine propulsion devices of the stern drive or inboard/outboard type, it is common to have hydraulic cylinder/piston assemblies connected between the gimbal ring and the propulsion unit for effecting tilting movement of the propulsion unit relative to the gimbal ring. On a typical stern drive application, two cylinders that respectively straddle each side of the propulsion unit are employed for effecting that tilting movement. Although use of two cylinders provides effective tilt/trimming operations, it will be appreciated that such laterally-straddling cylinders may create hydrodynamic drag affecting boat acceleration and fuel efficiency.
Thus, it will be desirable to provide a tilt/trimming assembly made up of a single cylinder that may be centered relative to the propulsion unit so as to avoid the hydrodynamic drag that may be created by the two laterally-straddling cylinders. It will be further desirable to reduce costs through the use of a single tilt/trim cylinder.
Generally speaking, the present invention fulfills the foregoing needs by providing in one exemplary embodiment a stern drive system having an outdrive rotatable about a generally horizontal axis to impart a desired trim or tilt to the drive system. The system comprises a gimbal ring that defines an inner region. A tilt-trim assembly is affixed to the outdrive, and the tilt-trim assembly has one respective end thereof pivotally supported by the outdrive. The assembly includes a single cylinder through the inner region of the gimbal ring and has one end thereof pivotally connected to the gimbal ring so that when the cylinder is actuated the outdrive is rotated about the generally horizontal axis.
The present invention further fulfills the foregoing needs by providing in another aspect thereof a method of assembling a tilt-trim assembly for use in a stern drive system generally disposed aft of a boat transom and having an outdrive configured to be rotated about a generally horizontal axis to impart a desired trim or tilt to the drive system. The method allows for executing the following actions:
receiving a first anchor pin to be pivotally supported by a respective gimbal ring defining an inner region;
affixing the tilt-trim assembly to the outdrive section;
receiving a second anchor pin at one respective end of the tilt-trim assembly to be pivotally supported by the outdrive, the assembly including a single cylinder having one end thereof connected to the first anchor pin so that when the cylinder is activated the outdrive may be rotated about the generally horizontal axis; and
positioning the cylinder so that its longitudinal axis intersects a respective axis that extends perpendicular relative to the generally horizontal axis and bisects the inner region of the gimbal ring.